1. Field of the Invention
The present invention relates to devices for blending, mixing and/or homogenizing the contents of a bag and, more particularly, of a sterile plastic bag holding clinical samples, for instance used in laboratories, in hospitals, in the food industry, etc.
2. Description of the Prior Art
It is well known to provide sterile plastic bags for holding samples, such as the plastic bag disclosed in U.S. Pat. No. 5,564,829 issued on Oct. 15, 1996 to Lafond. In this patent a disposable sterile plastic bag B is disclosed for holding samples in blenders during the mixing thereof, the bag B comprising a two-ply sheet flexible material integrally joined at opposed side edges thereof (or the bag may be made from a tube) and joined at the upper and lower ends thereof respectively by upper and lower heat seals with a sealed sample receiving chamber being defined between the two plastic sheets inwardly of the bag's side edges and upper and lower sealed ends. Inwardly of the upper seal, there is defined a tear-off line transversely across the two sheets and parallelly to the upper seal thereby forming a detachable strip outwardly of the tear-off line. When the sample is ready to be introduced in the bag, the detachable strip is removed from the bag by pulling it so as to cause rupture of the two sheets at the tear-off line. The bag's chamber is thus sterile when the sample is introduced therein and the bag and its contents can then be inserted in a blending machine, also called a homogenizer or a mixer. The bag's sterility does not depend on how the bag is packaged or on the integrity of the packaging's seal as the bag is itself sterile until the datachable strip is removed therefrom, that is until the bag is ready to be used.
Generally, commercial homogenizers or blenders used in laboratories to mix samples include a casing having a door which is pivoted to the casing and which, when open, reveal a chamber in the casing. In this chamber, there is provided paddles that are adapted to be repeatedly displaced by a motor. When the contents of a bag are to be mixed or blended, the door of the homogenizer is opened and the plastic bag and its contents are inserted into the homogenizer's chamber and the door is then closed such as to trap the upper end of the bag between the door and the casing while a lower portion of the bag and its contents are located in the chamber. The door, when closed, traps the upper end of the bag and thus firmly secures the same in a generally upright position in the homogenizer. The homogenizer is then switched on and the paddles, in a reciprocating movement, repeatedly pound the plastic bag and thus cause its contents to mix. After the homogenizer has been switched off, the door is opened and the bag is removed therefrom with the blended sample being now appropriately mixed and, for instance, ready for analysis.
In known homogenizers or blenders, the pivotable door cannot be removed from the rest of the blender. Furthermore, any rupture of the bag in the blender causes its contents to flow into the chamber of the blender and possibly onto the surface on which the homogenizer rests. This requires that the blender be extensively cleaned and there are some contamination risks in the laboratory.